A salt spray test defined in JIS Z 2371 and a cyclic corrosion test defined in JIS K 5600-7-9 have been known for the tests for evaluating the corrosion resistance of metallic materials used in the atmosphere.
Japanese Patent No. 4218280 also discloses a corrosion test procedure carried out in the simulated corrosion environment, to which test pieces are actually exposed, by adjusting the test conditions, such as the quantity of salt content to be deposited on the test pieces, and the temperature and relative humidity. The corrosion test procedure disclosed in Japanese Patent No. 4218280 involves a step of depositing a given quantity of salt content on the test pieces and a subsequent dry-wet cyclic step, in which a dry state and a wet state are cycled in preset temperature and relative humidity conditions. Both of these steps are repeated. According to the corrosion test procedure of the present invention, salt water adjusted to a given concentration is used as a chemical substance for accelerating corrosion and salt mist is sprayed on the test pieces to deposit salt content on the surfaces thereof.
On the other hand, Japanese Patent No. 3834630 discloses a corrosion test procedure, in which fine sea salt particles are formed by generating air bubbles in sea water.